An alarming increase in pediatric obesity has occurred in China, a developing country undergoing rapid economic transition. The prevalence was even higher in the developed metropolitan areas of China. The dramatic increase in the prevalence of obesity in children and adolescents has raised major concerns due to the long-term health implications. Pediatric obesity may increase morbidity as well as susceptibility to certain cancers in later life. Efforts to prevent obesity and maintain a healthy body weight has been recognized as one of most cost-effective long-term strategies for cancer control. Parents and the family environment play an important role in influencing adolescents' adoption and maintenance of healthy weight-related behaviors that regulate energy balance and ultimately obesity status. Certain characteristics of parenting styles, practices and family functioning may be influential in the development of obesity among adolescents. Even though some empirical studies, most with cross-sectional study designs, have provided preliminary data, there is an urgent need for rigorous investigations with longitudinal data for an improved understanding of these familial and parental characteristics and their roles in influencing management of weight-related behaviors and the risks of obesity in adolescents. There is a lack of research investigating the dynamic reciprocal relationships between multiple aspects of family functioning and obesity and related behaviors in adolescent populations. As obesity is not as widespread in China but is rapidly increasing, it is possible to study an epidemic of obesity in its earlier stags along with rapid social and economic development and the role of family relations in the process. We propose to systematically investigate longitudinal dynamic influences of critical parental and familial factors on adolescents' developmental risks of behavioral outcomes including obesity, eating behaviors and food consumption, physical activity and inactivity, and depressive symptoms with two existing longitudinal cohort datasets collected in representative samples of Chinese adolescents living in several major large cities in China. State of the art modeling approaches will be applied to analyze influence of family functioning and parenting characteristics in the developmental risks of behavioral outcomes and model the dynamic reciprocal relationships between family functioning and behavioral outcomes that may be both causes and consequences of each other during a certain longitudinal period. Potential interactive effects of parenting characteristics and family functioning as well as the potentially differential influences across parent-child gender will be explored to advance understanding of the heterogeneity of longitudinal familial and parental influences on the developmental risks of obesity and related behavioral outcomes. Findings of this study are expected to have the great potential to advance knowledge on the influences of parental and familial factors on the developmental risks of obesity and related behaviors during adolescence, which may guide to translate into the development of appropriate interventions as long-term strategies for cancer prevention and control.